Add User's Guide
Merge pull request #49 from denaitre/feature/users_guide

Add User's Guide
Added a user's guide generation target.
Merge branch 'feature/users_guide' of https://github.com/rozofs/rozofs into feature/users_guide
User's guide integration.
Include pictures
add style in about_rozofs.texi
Add index entries in about_rozofs.texi
[users guide] Add style in the second part of the user's guide
[users_guide] merge about_rozofs.texi
[users_guide] add content in 'Monitoring'
[users_guide] add style in 'Working with RozoFS'
[users guide] add index entries and corrections
[users_guide] last corrections and emphasize important words
added info_guide target.
added a logo and change filename.
modified html style.
escape brace for html target.
Remove cindex for docbook.
Add pictures to guide.